During the first Gulf War in the winter of 1990, Israelis huddled in sealed rooms and donned gas masks as Iraqi President Saddam Hussein lobbed Scud missiles at the Jewish state. Israeli intelligence knew that Hussein had a stockpile of chemical weapons and was worried that he might use them.

Now, more than 20 years later, Israelis are again worried about chemical weapons. This time, it is chemical weapons that the international community believes Syria possesses. If -- or when, according to many analysts -- the regime of Bashar Al-Assad falls, that stockpile of weapons could be up for grabs and terrorist groups including Hizbullah and Al-Qa'ida will be the first ones with their hands out.

"There will be pressure from Hizbullah and other organizations to get some chemical weapons," Ronen Hoffman of the Interdisciplinary Center (IDC) told The Media Line. "They are like eagles, just waiting for the opportunity to swoop down on their prey. It's an unbelievable opportunity for them."

Jordan's King Abdallah II also expressed concern that Al-Qa'ida could seize some of these weapons in an interview with CNN.

Israeli officials will not comment publicly on events in Syria saying only, as did Defense Minister Ehud Barak, that "Israeli is carefully monitoring events in Syria." But privately Israeli officials are concerned that Assad's fall could destabilize the region and give Hizbullah and Iran more power.

The Israeli-Syrian border has been Israel's quietist border since the end of the Yom Kippur war in 1973. If Assad falls, sectarian tensions between the majority Sunnis and the minority Alawites, who currently rule the country, could lead to chaos in Syria. During that chaos, Lebanon-based Hizbullah, a terrorist organization with a large fighting force and massive arsenal, could obtain some of the chemical weapons.

"This could be a real danger for Israel," Ephraim Kam of the INSS think tank told The Media Line. "Even if Hizbullah doesn't use the weapons against Israel immediately, it would give Hizbullah a large increase in deterrent power, and Israel would have to think twice before striking Hizbullah."

Israel and Hizbullah fought a war in 2006 after its operatives kidnapped two Israeli soldiers in a cross-border raid. The 34-day conflict left 1,300 Lebanese and 165 Israelis dead. Israel destroyed much of Hizbullah's short-range rocket capability, although Israeli intelligence officials say Hizbullah has since rebuilt and now has more weapons with greater range and payload capacity. Some estimates peg the number of Hizbullah missiles at more than 30,000.

Hizbullah also blames Israel for the assassination in 2008 of senior Hizbullah operations chief Imad Mughniyeh who was killed by a car bomb in Damascus.

But some Arab analysts say that it has not yet been proven that Syria has chemical weapons, or that Hizbullah is bent on getting them.

"Look at what happened in Iraq when the world insisted that Saddam Hussein had weapons of mass destruction, which was one of the main reasons for invading the country," Ayman Khalil, of the Center for Research on Arms Control and Security in Jordan told The Media Line. "And even if the current regime has chemical weapons, they will not be in the position of utilizing them in the current conflict. You have to have a trained group of military and technical experts to use them."

Khalil also said that Hizbullah is trying to achieve international legitimacy as a member of the Lebanese government and it is not in its interest to acquire a non-conventional capability.

Other experts say that the current fear over chemical weapons shows the mistake that the international community made by not intervening in Syria.

"The international community must organize a transition of power in Syria," Nadim Shehadi of the Chatham House in London told The Media Line. "For a long time, people were so afraid of what would happen in the aftermath of Assad. Now there is a change in outlook which is much more damaging to the regime. Assad staying in power has become the worse option."

Israeli analysts say chemical weapons in the hands of any radical group is dangerous.

"One option is to try to attack the chemical weapons and destroy them," Efraim Kam of the INSS said. "Alternatively, the US, which has a connection with the opposition, must ensure that the chemical weapons remain intact for whoever succeeds Assad."